PROJECT SUMMARY/ABSTRACT Dopamine is known to control mechanisms of information processing throughout the brain, including gain control, tuning, and sensitivity modulation. The role of dopamine signaling is particularly important in the olfactory bulb since there is a dense population of dopaminergic local interneuron and dopamine receptors are expressed on nearly all cell types. Behaviorally, pharmacological manipulations of dopamine receptor activity is known to influence odor discrimination and detection thresholds. However, where, when, and how in vivo dopamine release shapes neural circuit function to process odor information is not well understood. Building upon earlier in vitro experiments, this proposed work tests predictions about patterns of dopamine release in the olfactory bulb in vivo for the first time using cutting edge genetically encoded optical probes to monitor dopamine release. Spatiotemporal patterns of odor-evoked dopamine transmission in awake mice will be monitored to assess how stimulus intensity, frequency and experience-dependent plasticity shape dopamine transmission in the olfactory bulb. Experiments will test the levels of dopaminergic interneuron activity required to trigger dopamine release. In addition to measuring dopamine release, I will use a novel dual-color imaging approach to capture both dopamine transmission and dopaminergic interneuron dynamics simultaneously during awake odor processing.